1)
Why does it say "Lo Yitam'u"?
1.
Radak: It is Hispa'el (they will not become Tamei); it should say Yistam'u.
2.
Malbim: Initially the 10 tribes became Tamei via their idolatry, and Yehudah via "Pish'eihem". Similarly, during Bayis Rishon, they 1 became Tamei via idolatry, and in Bayis Sheni via their sins.
1
Perhaps 'they' refers to Klal Yisrael. (PF)
2)
Why does it say "v'Hoshati Osam mi'Kol Moshevoseihem"?
1.
Malbim: During Galus Edom, they sinned due to living among them. Hashem will save them from this.
3)
What do we learn from "Ehyeh Lahem lEi'lokim"?
1.
Malbim: I will conduct them with miraculous Hashgachah.
